Misleading variable name in exception handling

[progval]

BPO	26845
Nosy	@vstinner, @progval, @isidentical

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-12-20.19:10:58.923>
created_at = <Date 2016-04-25.19:56:07.400>
labels = ['interpreter-core', 'invalid']
title = 'Misleading variable name in exception handling'
updated_at = <Date 2019-12-20.19:10:58.922>
user = 'https://github.com/ProgVal'

bugs.python.org fields:

activity = <Date 2019-12-20.19:10:58.922>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2019-12-20.19:10:58.923>
closer = 'vstinner'
components = ['Interpreter Core']
creation = <Date 2016-04-25.19:56:07.400>
creator = 'Valentin.Lorentz'
dependencies = []
files = []
hgrepos = []
issue_num = 26845
keywords = []
message_count = 3.0
messages = ['264198', '358716', '358728']
nosy_count = 3.0
nosy_names = ['vstinner', 'Valentin.Lorentz', 'BTaskaya']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue26845'
versions = ['Python 3.6']

[progval]

In Python/errors.c, PyErr_Restore is defined this way:

void
PyErr_Restore(PyObject *type, PyObject *value, PyObject *traceback)

In Python/ceval.c, in the END_FINALLY case, it is called like this:

PyErr_Restore(status, exc, tb);

I believe “exc” should be renamed to “val”.

Indeed, END_FINALLY pops values from the stack like this:

PyObject *status = POP();
// ...
else if (PyExceptionClass_Check(status)) {
     PyObject *exc = POP();
     PyObject *tb = POP();
     PyErr_Restore(status, exc, tb);

And, they are pushed like this, in fast_block_end:

PUSH(tb);
PUSH(val);
PUSH(exc);

[isidentical]

I am not sure if calls like this constitutes a problem. By the way most of the things changed in Python/ceval.c including removal of END_FINALLY (bpo-33387) but calls to _PyErr_Restore is still there with that same arguments.

[vstinner]

Variable names have no impact on the execution. Sometimes, it's called "exc", sometimes "val", sometimes "exc_val" :-) This issue is not a bug.